ISIS in 2016: smaller, darker, colder — and more desperate.

It was a rare and remarkable week that sent the Islamic State group stumbling into 2016, taking territorial hits from multiple directions.

In Iraq, a struggling army finally unclenched the grip of Islamic State over the ravaged city of Ramadi, the capital of Anbar province, in an operation paved with American airstrikes.

On the Syrian side, a broad new front opened fast and wide, with mostly Kurdish fighters leading a four-day sweep south from Kobani, snipping another 640 square kilometres from the caliphate’s map, threatening supply lines and seizing back a key piece of infrastructure, the Tishrin Dam.

Online, Islamic State had a hilariously rare stumble, with the viral mocking of leader Abu Bakr al-Baghdadi’s call on Boxing Day for Muslims worldwide to join the fight. (Among the sharper responses, via Twitter: “Sorry, I’m busy being a real Muslim, giving to charity, etc. Also your dental plan sucks.” #GoatTeethISIS.)

But the more telling development passed largely unnoticed — an exceptionally thorough exposé by the Iraq Oil Report that showed how Islamic State, believed by many to be awash in the proceeds of crude, is in fact nearly running on empty.

Islamic State was rich — in the beginning — siphoning and smuggling oil worth as much as $40 million a month. But then the U.S. got its hands on nearly seven terabytes of data during a special forces raid in May that spelled out how the group had placed oil at the very centre of its existence. At its peak, Islamic State managed a 21st-century operation involving more than 200 producing wellheads, profiting directly in black market sales and profiting again through a series of taxes levied along the distribution chain.

That trove of data, the IOR investigation shows, changed the U.S. air campaign significantly, leading to a sustained series of strikes since October that have wreaked havoc with Islamic State oil operations. The report corroborates those claims with first-hand testimony of residents and oil workers within the caliphate’s territory.

On the Iraqi side, Islamic State now mines and refines what it can in open pits, 17th-century style: “They essentially dig holes in the ground in which they heat up the oil through a rudimentary still,” the IOR reports.

U.S. targeting of tanker trucks added to the pressure, as did the slide in global oil prices. But the clearest indication of the strain on Islamic State finances is the spiralling cost of fuel in areas under its control. In Fallujah, for example, gasoline is now double the price of what it is in nearby Baghdad, and household fuel is so scarce “some residents say they are heating their food by dismantling their doors for firewood.”

In a continuing saga so clouded by propaganda on all sides — and festering now as a two-country war cluttered with proxies from throughout the region and beyond — there are still plenty of reasons to view the fight against Islamic State as a glass half full or a glass half empty.

The taking of Ramadi by the Iraqi army, for example, merely sets the stage of another test of the Shiite-dominated Iraqi government’s ability to govern across sectarian lines. A test it has failed repeatedly since the Americans toppled Saddam Hussein.

The new encroachment against Islamic State from the Syrian side, meanwhile, is still a largely Kurdish effort — and one unlikely to bring siege to nearby Raqqa, the de facto capital of Islamic State, without a battle force that includes more than token representation from Syrian Arabs.

But as Syria’s embattled factions and their outside allies embark on a new round of talks in Vienna aimed at ending the civil war, whatever faint hope exists for a political breakthrough in 2016 now should be measured against a far better understanding of Islamic State’s financial frailty, as the flow of oil dries up.

Islamic State — the actually territory, if not the idea — looks to become a colder, darker and more desperate place in 2016, as it struggles for fuel. It might not be a question of the glass half-full versus half-empty. It might boil down to a question of nothing left in the tank.